Errors

Connect-Swift uses a set of 16 error codes. These are similar to the "404 Not Found" and "500 Internal Server Error" HTTP status codes that you're likely familiar with.

In the Connect protocol, an error is always represented as JSON. For example:

HTTP/1.1 400 Bad Request
Content-Type: application/json

{
    "code": "invalid_argument",
    "message": "sentence cannot be empty"
}

Connect-Swift provides a common ConnectError type that represents errors consistently across all supported protocols.

ResponseMessage values returned by unary API calls expose an optional ConnectError?, and StreamResult values returned by streaming APIs can also contain this type:

let request = SayRequest.with { $0.sentence = sentence }
let response = await elizaClient.say(request: request)
if let error = response.error {
    print(error.code) // Code.invalidArgument
    print(error.message) // "sentence cannot be empty"
    print(error.metadata) // Dictionary of additional server-provided headers/trailers
}

Error details

Additional strongly typed errors may be specified by the server in responses. These are wrapped with the google.protobuf.Any type on the wire, and can be unpacked using the ConnectError.unpackedDetails() function by specifying the expected error message type (Eliza_V1_ChatError in this example):

let request = SayRequest.with { $0.sentence = sentence }
let response = await elizaClient.say(request: request)
if let chatErrors: [Eliza_V1_ChatError] = response.error?.unpackedDetails() {
    // Handle the custom errors
}

Cancelation

Canceling an outbound request (i.e., by canceling an async Task or by calling cancel() on a callback-based request) will result in a response containing the canceled error code:

let request = SayRequest.with { $0.sentence = sentence }
let cancelable = elizaClient.say(request: request) { response in
    print(response.code) // Code.canceled
}
cancelable.cancel()